Directional antenna system



CROSS REFERENCE May 3, 1938.

K. SCHMID v DIRECTIONAL ANTENNA SYSTEM Filed May 22, 1936 INVENTOR KURT S HMID BY ATTORNEY Patented May 3, 1938 UNITED STATES PATENT OFFICE DIRECTIONAL ANTENNA SYSTEM Germany Application May 22,

1936, Serial No. 81,181

In Germany June 4, 1935 2 Claims.

The present invention is concerned with a weatherproof arrangement for ultra short waves. In the mounting of antennae it happens quite often that their proper operation is seriously im- 5 paired by the inclemencies of the weather, bird excrements and dead insects. It has been suggested to accommodate the entire antenna assembly, that is to say, radiator, including reflector or tube, inside a box casing permeable to electrical waves. Although the antenna assembly is safeguarded from the efiects of the weather, one shortcoming of this idea is that the large surfaces of the box offer a high resistance to the wind. Another disadvantage is that the expenditure for material is so great that it does not warrant the aim. According to the present invention, only th radiator or radiators are accommodated inside a casing protecting the same against atmospheric agencies, and that the reflector is built according to aerodynamic principles.

An exemplified embodiment of the basic idea of the invention is illustrated in Fig. 1. Fig. 2 shows a detail of Fig. 1.

Referring to Fig. l, in the focal line of the cylinder paraboloid P is a tube R. which is closed all around and made of insulation material, there being confined in the interior of the said tube a dipole radiator D. The feed line S passed through the reflectoris confined inside the metallic pipe M for the sake of shielding. In such cases, Where metallic shielding is not absolutely necessary, the feeder S could be shielded also by lighter and cheaper material. Now, in order to minimize the wind resistance of the parabolic mirror, the same is not made from sheet metal, but rather from a gauze or wires extending parallel to the dipoles.

The way the pipe or tube enclosing the dipoles D should preferably be made is illustrated in Fig. 2. For the sake of simplicity, only one pair of dipoles D is here illustrated which is directly united with the feeder S. The feeder for the purpose of shielding it is laid inside the metallic tube M which at point 0 is passed through the reflector (not shown). The pair of dipoles D is placed in the tube J made of insulation material, which at both ends is shut by lids V though the same is shown cut open at the bottom end. Now, inasmuch as it is suitable in the case of parabolic reflectors to mount in front of the dipoles a small auxiliary reflector, the part H of tube J according to this invention may be made of metal or else is metallized inside and out.

The embodiments here described embodying the idea of this invention offer the advantage that with limited means the radiators are safeguarded from atmospheric agencies and from soiling by animals, while yet causing but little wind resistance.

It will be evident that the basic idea of the invention is not confined to the instances here discussed. For instance, also individual dipoles and rows of dipoles of a Christmas tree type of directional antenna could be placed inside a tube to be safeguarded from the weather or some similar enclosure or container and the posterior reflector could be built up of a number of parallel wires. It will be understood that the invention could be applied also to antenna arrays comprising rotary paraboloids, etc.

What is claimed is:

1. In combination, a reflector, a dipole antenna at the focus of said reflector, said dipole having two arms arranged substantially in the same straight line, a feed line connecting the adjacent ends of said arms with high frequency apparatus, a hollow insulating tube completely surrounding said antenna and having an aperture located in the center thereof for entrance of said feed line, and a metallic shield surrounding said feed line for at least a portion of its length adjacent said insulating tube.

2. In combination, a reflector comprised of perforate metallic material, an antenna at the focus of said reflector, a feed line connecting said antenna with high frequency apparatus, a hollow insulating tube completely surrounding said antenna, and a metallic shield surrounding said feed line for at least a portion of its length, that portion of said insulating tube farthest removed from the center of said reflector having a metal surface for reflecting towards said reflector rays emanating from said antenna and striking said surface.

KURT SCHMID. 

